The invention relates to a subsurface exploratory radar detector for a hand tool device such as a percussion drill or a chipping hammer.
The use of a hand tool device when working with masonry embedded with electrical wiring, plastic piping, etc. and steel reinforcement requires knowledge of the presence, the nature, and the location of such lines or steel or iron reinforcement relative to the tool. Such knowledge is important because such embedded objects could damage the tool. Further, such knowledge is important to properly carry out the work, i.e., placement of dowel fastener holes with minimum clearance from lines or steel reinforcements.
U.S. Pat. No. 5,541,605 discloses a subsurface radar detector for detection of reinforcement iron and steel in concrete, wherein the detector operates in the ultra-wideband range and is swept over the surface.
According to U.S. Pat. No. 5,051,748 discloses a portable ground penetrating radar detector operating in the microwave range for the detection of reinforcement iron and steel in concrete. The disclosed radar detector comprises an antenna array with wave guides arranged in intervals along a line, whose pin-hole antennae directly produce a line image which, with a movement of the antenna array diagonally to the direction of the array and in conjunction with a computer, produces a flat image of the buried object, whose image is then displayed on an image output device.
U.S. Pat. No. 5,900,833 discloses a portable radar detector equipped with a synthetic radar antenna (SAR xe2x80x9csynthetic aperture radarxe2x80x9d) whose signals are initially processed in signal processors. The radar detector can produce three-dimensional images of objects buried underground, such as reinforcement steel. Moreover, the images are represented on an image display device. The individual antennas, which need not necessarily be arranged linearly, are moved diagonally to the antenna array to produce a synthetic aperture with the radar detector.
U.S. Pat. No. 5,512,834 discloses a portable subsurface exploration radar detector that detects electrical lines, plastic pipelines, and reinforcement steel when creating bore holes. The radar detector sends and receives narrow band, periodically modulated electromagnetic waves into and from the subsurface area being explored for objects arranged in a near field area. The radar detector makes possible adjustment for depth and provides area resolution by evaluating the pulse forms and the geometry and intervals of the associated antennas of two complete detectors or the receiving antennas of a common transmitter. Depending on the results of the detection, a hand tool, such as a nail gun tool, to which the detector is attached, is controlled automatically via the nail dispenser. Objects that are closely adjacent to one another; for example, those arranged in grids, cannot be oriented with sufficient precision by the two spaced receiving antennas. Similarly, no information is received on the orientation or the depth of embedding of the buried objects.
The object of the present invention is to provide a subsurface exploration radar detector that is simple to use and can be mounted on the hand tool for the detection of embedded objects situated in close proximity to one another.
This object is achieved, in accordance with the invention, by a radar detector that explores subsurface embedded objects comprising an antenna array for high-frequency electromagnetic waves with at least three antennas having at least one transmit/receive unit. The at least one transmit/receive unit is connected to at least one timed signal processor for paired temporal correlation of the demodulated signals and the one time signal processor is connected in an information transferring manner with an evaluation unit for SAR for resolution of the demodulated signals and to a display device. Moreover, the at least three antennas by their positions together scan an area and wherein the at least three antennas are switchably connected with at least one transmit-receive device.
In essence, a subsurface exploratory radar detector, in accordance with the invention, exhibits at least three high-frequency electromagnetic wave antennas whose positions sweep an area together and which are individually connected with transmit and receive units. The demodulated signals of such antennas can be processed in paired temporal correlation and combined evaluation in a time-controlled signal processor, wherein the processor is in an evaluation unit for SAR and is connected to a display device.
The paired temporal correlation of two of the at least three antennas arranged on a surface and the combined evaluation thereof enables the position in space of buried or embedded objects to be determined without having to reposition the radar detector.
Advantageously, exactly two of the at least three antennas are temporally shifted by the control unit as a transmit-receive antenna pair switchably connected with the radar transmitter or the radar receiver, whereby only one radar transmitter and one radar receiver is required.
Also, at least two antennas are polarized differently relative to each other, whereby the orientation of an elongate object can be ascertained by paired temporal correlation and combined evaluation.
The antennas that arc polarized parallel relative to each other are linearly arranged and the two rows are arranged in the shape of an xe2x80x9cXxe2x80x9d (lit. cross shape). Along each row, the transmit and receive antenna pair that is switchably connected with the radar transmitter or with the radar receiver can be repositioned.
At least three antennas that are polarized parallel relative to one another are arranged in at least one row, whereby two transmit and receive antenna pairs can be switched to different spacing relative to each. In such an arrangement, the depth of embedded objects can be determined independent of the propagation velocity of the radar waves in the subsurface.
The antennas, arranged crosswise in two rows, are further arranged in central symmetry relative to each other, thereby simplifying evaluation.
Also, the arrangement of the antennas in the centrally-symmetrically cross shape forms an empty space at the central intersection, into which a tool can be inserted.
Advantageously, through the evaluation of the characteristic of the reflected radar waves between different materials, for example, plastic and iron, embedded objects can be distinguished and displayed, for example by light-emitting diodes (LED).
The evaluation unit is configured as a neural network, which represents the plurality of combined, paired temporal correlation to be interpreted as an input variable in a numerically limited number of classifications, that are divided into:
centrally punctuate/discrete
vertically elongate
transversely elongate
horizontally elongate
centrally crossed
and
no object
and the classifications are displayed, for example, using an LED.
Also, the depth of the embedded object is displayed on a discrete scale.
Further, all the information is displayed together on a small graphic display.
Moreover, a parameter, such as maximum drilling depth, is transferred from the hand tool and the parameter is taken into consideration in the interpretation.
The classification is transmitted by the evaluation unit as a control signal to the hand tool and utilized by the hand tool for blocking or releasing a work process, for example, drilling.